. >>> new assurances this week from nasa that the world will not end on december 21st. people around the globe are stockpiling supplies just in case. joining me now an astronomy professor in california. thank you for being here. i'm so glad to talk with you about this. there's so much attention on this mayan calendar. supposedly signalling an end to the world on december 21st. what's the truth, andrew, behind this calendar? does it really predict the world's end? >> i like to call this fiction science instead of science fiction. this is completely baseless. there's not a shred of evidence in favor of it. but it sure is a lot of fun to be worrying about the end of the world. hollywood knows that, too. as far as the mayan calendar is considered, alex, this is a complete misunderstanding of how calendars work. look, we faced this kind of calendar cliff every year when on december 31 you run out of pages on your calendar. you don't think it's the end of the world. you just think it's time to go to the stationery store and buy a new calendar. we are according to some experts